Audion construction



Jan. 2, 1934. F, L. HUNTER, JR 1,941,687

' AUDION CONSTRUCTION Filed April 8, 1927 as iwzaum Z Patented Jan. 2, 1934 UNITED STATES PATENT OFFICE} AUDION CONSTRUCTION Application April 8, 1927. Serial No. 182,079

12 Claims.

This invention relates to an improved audion construction.

One of the objects of this invention is the provision of an audion having a novel device for emitting electrons and a novel method of heating the same.

Another object of this invention is the provision of a cathode which has an increased area for emitting electrons.

A further object of this invention is the provision of a new unit comprising a heat source and an electron emitting source with a novel method of supporting the same which support provides a heat path for conducting the heat from the heating body to the electron emitting body.

These and many other objects are sought by means of the construction disclosed herein.

This invention resides substantially in the combination, construction, arrangement and 2 relative location of parts as will appear from the following disclosure.

Referring to the drawing Figure 1 is a side elevational view of a device employing the principles of this invention.

Figure 2 is a view taken at right angles to that of Figure 1 with one of the plates removed to disclose the interior construction of the device.

Figure 3 is an enlarged perspective view of the construction and relative arrangement of the 30 electrodes with the grid removed.

Figure 4 is a perspective view of the heating element, and

Figure 5 is a perspective view of the cathode or electron producing element.

There has been sought for sometime an improved construction of audion or vacuum tube devices for use in radio circuits whereby an alternating current may be employed for heating the cathode. I-Ieretofore this has been impossible because of the undesirable hum introduced into the output circuit of radio apparatus when the alternating current is applied directly to the filament of the audions. There have been constructed devices which employ alternating current for heating them, but it has been found in practice that they are very inefficient and it is the purpose of this invention to provide a novel arrangement of elements in combination with a novel electron emitting element to produce a practical device which is simple and easy to construct and efficient in operation.

Referring to the drawing, a device constructed in accordance with my invention is shown in Figure 1 comprising a base 1 having the terminals 2 with the usual and well known construction, a

glass envelope 3 and the stem tube 4. At 5 is shown a block of suitable insulating material such as isolantite. Extending through the center of the block 5 is a suitably shaped channel 6. Extending longitudinally of the block and each side thereof are the grooves '7 having inclined edges as shown. Mounted within these grooves are the cathode or electron emitting members 8 which are constructed as will be described below. A grid 9 is shown encircling the block 5. It will be noted that the members 8 terminate slightly below the surface of the block so as to be out of contact with the grid. Mounted in the channel 6 is a suitable heating body 10 which may be called a filament if desired. The heating body 10 is supported at two ends by means of the rods 11 which are secured in the stem tube 4. In the construction shown by me the rods 11 comprise a support for the block 5, the heating body 10, the cathodes 8 and the grid 9 by forming a compact unit. The heating body 10 is provided with a series of slots 12 so as to reduce the current carrying section of the member 10 to a point where the resistance is sufiiciently increased so that the heating body will produce the proper amount of heat for a given set of conditions. Supported on each side of the block 5 are the plates 13 which are supported in the stem tube in a suitable and well known manner and which are pressed and secured together by means 5 of the transverse strips 14. The cathodes 8 are made by mixing together nickel and/or platinum powder with salts of barium or other active compounds such as calcium, cerium and the like. These powders are 9 mixed together and compressed in a die under a very great pressure to produce a coherent homogeneous mass. The body thus formed is then sintered or melted in a vacuum to produce an electronic active element. 95

It will be evident that the areas of the cathodes 8 may be varied to suit any desired conditions and further the relative size and arrangement of the parts may be varied without 400 departing from the scope of this invention. I do not desire to be limited to the exact details of construction disclosed by me for'illustrative purposes since I am aware that many changes in the details of construction will readily occur to 105 those skilled in the art. The constructions as disclosed by me have been merely for the purpose of illustrating the principles of my invention and I, therefore, only desire to be limited as required by my appended claims.

What I seek to secure by United States Letters Patent is:

l. A cathode construction for audions comprising a block of insulating material having heating means imbedded therein and slabs of electronically active material supported on said block in grooves formed on the surface thereof.

2. A cathode construction for audions comprising a block of insulating material having'heating means imbedded therein and slabs of electronically active material supported in grooves on said blocks so as to be below the surface thereof.

3. In an audion construction the combination with an envelope of a single block of insulating material having grooves supported Within said envelope, heating means imbedded in said block, electron emitters mounted in the grooves and a control member adjacent said block.

4. In an audion construction the combination with an evacuated envelope a block of insulating material having grooves supported Within said envelope, heating means imbedded in'said block and passing therethro eicctron emit ters mounted in the grooves and a control member encircling said block emitters.

5. In an audicn construction thecombination with an evacuated envelope of a block of lating material having grooves supported within said envelope, heating means imbedded in block and passing therethrough, rec-tron emitters mounted in the grooves a control inember encircling said block and em'rters supported thereby.

6. In an audion construction the combination with an exhausted vessel of an innilating member, heating means imbcdded in said member and supporting it and electron emitting bodies mounted in grooves on said member.

'7. In an auction construction the combination with an exhausted vessel of an insulating mere: ber, heating means imbedded in said member andv supporting it, electron emitting bodies on said member, a control member supported on said insulating member and a plate structure adjacent said control member.

8. In an audion construction the combination with an evacuated envelope of a unitary structure mounted in said envelope comprising a sup- 9. In an audion construction, the combination with n evacuated envelope of a plurality of electrodes including thermionic electron emitter acting as a primary source of electrons, a control grid and an anode, a single block of insulating mat rial for supporting at least two of said electrodes, said emitting electrode being supported on the outer surface of said insulating block, means supported by said block and'separate' from said emitter for heating said emitter, said grid and anode being supported in freely spaced relation so as to receive electrons direct from said emitter.

10. In an audion construction, the combination with an evacuated envelope of resistance heating means, an insulating block containing said heating means, electron emitter supported by said block and direct contact with the surface thereof and a grid and plate surrounding said emitter, grid and plate being freely spaced from each other, said gridbeing supported by said block.

11. In an audion construction, the combination with an evacuated envelope of a plurality of mCl fOdS therein, one or" said electrodes being an electron emitter, a heat conducting body in which said emitter electrode is mounted and in FREDERICK L. HUNTER; JR

said

thereof, a

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